Drawbridge



( N0 MOdeL) N. C.'JBSSUP. DRAWYBRVIDGE. 1

N0. 514,754; Patented Peb. 13, 18194.

' brace the platform that its outer or forward NATHAN c. JEssUP, oF wEs'rHAMProN BEACH, NEW YORK.

DRAWBRIDGE.

lS1.EGIIEIG'A {lIOlNl' forming bart of Letters Patent No. 514,754, dated February 13, 1894. Application filed March 23, 1892. Serial No. 426,065. (No model.)

endwise movable platform adapted to be projected across the draw by devices adapted to be operated on one side of the draw; and the objects in view are, irst, to so sustain and guide the endwise movable platform that it cannot be accidentally deflected from its operative position, and secondly, to 'so truss and end will not be unduly raised or lowered while in the act of projecting the platform across the draw, or withdrawing it to one side of the draw to open the latter.

To the accomplishment of the first part of my invention,I provide three series of rollers arranged in the line of and parallel with the longitudinal axis of. the platform, the central series of rollers, havingianges, and the two side series of flangeless rollers, combined with a platform having, on itsv lower side, three longitudinal rails, the middle rail being fitted and guided between the anges of the central series of rollers, and the two side rails bearing and riding on the flangeless rollers on opposite sides of the central flanged rollers, and operating mechanism for moving the platform in the direction of its length.

Heretofore a draw bridge has been supported on three sets of flanged parallel guide rollers the rails on the platform fitting into and traveling between the dan ges on each set of rollers; but I have found this construction is open to the serious objections that the rails will bind on the flanges of the rollers when moved laterallyby a weight on the rear end of the platform, by the force of the wind blowing against one side or the other of the bridge, by the warpage of the wood work, by unequal tension on the truss rods, &c. A bridge constructed in accordance with my invention overcomes these objections.

My invention further consists in a platform having its rails guided between the central anged rollers and kriding uponthe smooth side rollers, two longitudinal tension rods attached to the ends of the platformand provided With turn buckles, and a transverse tension rod arranged underneath the forward free end of the platform, attached to the sides thereof, and provided with two turn buckles, whereby the platform can be held under such tension that its forward free end will notv be unduly depressed or raised, nor move out of its proper line, when it is projected or withdrawn.

To enable others to readily understand my invention, I have illustrated the samein the accompanying drawings, in which- Figure l is a side elevation of a bridge embodying my'improvements showing the draw open. Fig. 2 is a longitudinal sectional view of the bridge .platform and its actuating mechanism taken on the line oc-x of Fig. 4. Fig. 3 is a top plan view of the movable plat` form, and Fig. 4.- is a transverse sectional view showing the bridge platform and the actuating means in elevation.

Referring to the drawings, in which like letters of reference denote corresponding parts in all the figures, A designates the bridge or other structure having a draw a, and B is the movable platform adapted to be projected across the draw, as will appear hereinafter. Journaled in suitable bearings on either side of the structure A are a number of carrying rollers o/ arranged in two series longitudinally of the platform B, and they are adapted to sustain the longitudinal beams or side timbersof theplatform. Theserollersaresmootli faced, but in the middle of the structure is another series of guide rollers b each having two side flanges b on the sides, projecting beyond the face.

The movable platform B is of sufficient length and width to properly extend across the draw a. On either side of the platform,

near the forward end thereof, is an upright or standard C and a brace wire or stay c is secured to the platform in front and rear of the upright and runs over the top of said upright,

ICO

said stay being provided with a turn-buckle c to adjust the tension of the wire. The rear ends of the stays are secured to the platform behind the middle thereof, so. that the stays assist in holding the forward end of the platform elevated while it is being projected across the draw. Secured 011 the bottom of the movable platform are three rails D, D', the two outer rails I), D, running ou the smooth-faced rollers a', and the center rail D running on the guide rollers b and between the flanges b thereof. Under the front end of the movable platform are two braces E having turn-buckles e, which are secured to either side of the platform in .a suitable place and to the middle rail D. Without these transverse braces E, the side stays would tend to draw the sides of the platform up and depress the middle; but these two braces avoid such objectionable features, and assist the side stays in holding the platform elevated. On the rear end of this platform is an ineline d which is hinged or otherwise secured to the movable platform and it is also provided with two or more rollers d to facilitate its movement.

On one side of the structure A at or near the draw,is a short powershaft F supported on an upright f and carrying a balance or power wheel f and gear wheel f. Another shaft G is journaled in suitable bearings on the structure, and it carries a gear wheel on each end, one of which gears g, meshes with the gear f and the other g' engages with a toothed rack bar H secured on the bottom of the platform. By this simple construction the platform B may be readily projected across the draw and returned as desired, and the stay wires c and braces E, together with the weight of the rear end of t'ne platform and the hinged section, hold the forward end elevated so that it will assume its proper position on the other side of the draw and prevent it from sagging, zc.

I am aware that changes in the form and proportion of parts and details of construction of my invention may be made without departing from the spirit or sacrificing the advantages thereof, and I'therefore reserve the right to make such changes as fairly fall within the scope of the same.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a draw bridge, substantially such as described, the series of central flanged guide rollers, supported in suitable bearings on the structure A, and the two series of flangeless smooth bearing rollers a situated on opposite sides of said flanged guide rollers b, combined with a platform provided with longitudinal rails, the middle rail resting between the flanges of the central series of rollers l?, the two side rails bearing upon the smooth rollers a', and suitable operating means for moving the platform endwise across the draw, as and for the purposes described.

2. In a draw bridge, the combination with the structure A provided with the three series of rollers a l9,the central flanged rollers I) and the side flangeless rollers of the platform having its longitudinal rails resting on the series of rollers a', b, and the central rail fitting between the flanges of the rollers l),

the longitudinal tension rods c secured to the ends of the platform and provided With the turn buckles, and the transverse tension rods E secured to the sides of the platform at the forward free end thereof and having the turn buckles e, substantially as and for the purposes described.

In testimony whereof I allix my signature in presence of two witnesses.

NATHAN C. JESSUP.

Witnesses:

GEORGE H. FRASER, CHARLES K. FRASER. 

